The present invention relates to a photosensitive resin composition for forming a polyimide film pattern used in a semiconductor device. 2. Description of the Related Art
A passivation film is formed in general on the surface of a semiconductor device in order to protect the device from the external environment and to improve the reliability of the device. A polyimide resin excellent in electrical properties such as an insulating property and in the resistance to heat is widely used as a material of the passivation film. The polyimide resin is also used widely for forming an interlayer insulating film included in a multilayer interconnection structure of the semiconductor device.
A passivation film or interlayer insulating film of polyimide is prepared as follows. In the first step, the predetermined surface of a semiconductor device is coated with varnish of polyamic acid, i.e., precursor to the polyimide resin. Then, the coating is subjected to a heat treatment. As a result, the polyamic acid is subjected to a cyclizing reaction so as to be thermally set and, thus, to form a desired polyimide resin film.
In many cases, it is necessary to pattern the passivation film and the interlayer insulating film included in a semiconductor device. In general, PEP (photo engraving process) using a photoresist is employed for patterning the polyimide passivation film and interlayer insulating film. To be more specific, a polyimide film is formed first on a semiconductor substrate as described above, followed by forming a photoresist film on the polyimide film. The photoresist film thus formed is exposed to light and, then, developed so as to form a resist pattern. Further, a selective etching is applied to the polyimide layer with the resist pattern used as an etching mask so as to form a polyimide passivation film or interlayer insulating film of a desired pattern.
In the conventional method of forming a polyimide passivation film or interlayer insulating film of a desired pattern, however, it is necessary to employ independently the step for forming the polyimide film and the pattern forming step utilizing PEP, leading to a complex process for forming a polyimide film of a desired pattern.